This application describes a study of the functional organization of a mammalian retina in which the physiological response of the various types of neurons will be directly matched with their morphology and synaptology. The project includes: 1) studying the physiology of bipolar, amacrine, and ganglion cells by intracellular recording technique in the isolated rabbit retina eyecup preparation; 2) injecting horseradish peroxidase (HRP) into the cell which has been physiologically identified and studied; 3) cytochemically staining the tissue for HRP to localize the cell; 4) making a camera lucida drawing and a computer graphic three-dimensional reconstruction which enables the same cell to be examined in both the "en face" and "profile" views; 5) embedding the labeled cell in plastic to be serially thin sectioned for examination of its synaptic connections with the election microscope. The problems to be investigated are: 1) anatomical identification of on and off bipolar cells, and the nature of their synaptic contacts in the outer and inner plexiform layers; 2) polarity of the rod bipolar cell response and its influence on the on and off pathways of the retina; 3) physiological characterization of the various morphological types of amacrine cells; 4) functional significance of the synaptic arrangements in the inner plexiform layer, i.e. dyad, reciprocal, and serial synapses; 5) identification of the morphological counterpart of the various functional types of ganglion cells and electron microscope analysis of their connections.